12-hour clock

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A typical analog 12-hour clock

The 12-hour clock is a way of dividing the 24 hours of the day into two sections. The two halves are called ante meridiem (a.m.) and post meridiem (p.m.).

Both names are from Latin, and numbered from 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. Time from midnight to noon is a.m. and from noon to midnight p.m. The table at right shows how it relates to the 24-hour clock. Most places in the world use a 12-hour clock for their normal working lives. However in Canada and the US their military uses the 24-hour system.

24-hour clock 12-hour clock
00:00 12:00 a.m.

(midnight)

01:00 1:00 a.m.
02:00 2:00 a.m.
03:00 3:00 a.m.
04:00 4:00 a.m.
05:00 5:00 a.m.
06:00 6:00 a.m.
07:00 7:00 a.m.
08:00 8:00 a.m.
09:00 9:00 a.m.
10:00 10:00 a.m.
11:00 11:00 a.m.
12:00 12:00 p.m.

(noon)

13:00 1:00 p.m.
14:00 2:00 p.m.
15:00 3:00 p.m.
16:00 4:00 p.m.
17:00 5:00 p.m.
18:00 6:00 p.m.
19:00 7:00 p.m.
20:00 8:00 p.m.
21:00 9:00 p.m.
22:00 10:00 p.m.
23:00 11:00 p.m.
24:00 12:00 a.m.

(midnight)